Add docs for MCAP export

docs/EXPORT.md

@@ -2,9 +2,9 @@
 
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-AdvantageScope includes a flexible system for exporting log data as a CSV or WPILOG file. The export functions work when viewing a log file or when connected to a live data source. Possible use cases include:
+AdvantageScope includes a flexible system for exporting log data as a CSV, WPILOG, or MCAP file. The export functions work when viewing a log file or when connected to a live data source. Possible use cases include:
 
-- Converting a WPILOG file to CSV for analysis in other application.
+- Converting a WPILOG file to CSV or MCAP for analysis in other applications.
 - Exporting a WPILOG file based on NetworkTables data, for later access.
 - Saving a WPILOG with a limited number of fields (and duplicate values removed) to reduce file size.
 
@@ -18,6 +18,7 @@ The following options are provided when exporting:
   - _CSV (Table):_ Comma separated values, where each row represents a distinct timestamp and each column represents a field (plus a column for the timestamp value). Each row can represent a change in multiple fields.
   - _CSV (List):_ Comma separated values, where each row represents a change in a single field with columns for timestamp, key, and value.
   - _WPILOG:_ Standard WPILOG file that can be opened again in AdvantageScope.
+  - _MCAP:_ Standard [MCAP](https://mcap.dev) file that can be opened in [Foxglove](https://foxglove.dev). Note that structured data is not supported for MCAP exports.
 - **Timestamps:** Only for "CSV (Table)". Sets the method for creating new rows. See options below.
   - _All Changes:_ Create a new row when any of the included fields are updated. Other columns will show duplicate values.
   - _Fixed:_ Create new rows at a fixed interval, useful for logs without timestamp synchronization (when many fields are being logged with similar, but not identical, timestamps).
@@ -27,7 +28,7 @@ The following options are provided when exporting:
   - "_Flywheels,DS:enabled_": Include all fields starting with "/Flywheels" or "DS:enabled" (all data from the flywheel, plus the robot's enabled status).
   - "_Drive/LeftPosition,Drive/RightPosition_": Only include the fields "/Drive/LeftPosition" and "/Drive/RightPosition".
 
-> Note: Exported log files may not exactly match the original data. Duplicate values recorded in the original log file are discarded, and are not included in the "CSV (List)" and "WPILOG" formats. This effect can be used to reduce the size of WPILOG files with duplicate values, by opening and then exporting again with the "WPILOG" format.
+> Note: Exported log files may not exactly match the original data. Duplicate values recorded in the original log file are discarded, and are not included in the "CSV (List)", "WPILOG", or "MCAP" formats. This effect can be used to reduce the size of WPILOG files with duplicate values, by opening and then exporting again with the "WPILOG" format.
 
 An example CSV file exported from AdvantageScope is shown below, in the "CSV (Table)" format with timestamps set to "All Changes":